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(No Model.) 2 Sheets-Sheet 1..

W. J. GREEN.

TELEPHONE SYSTEM. No. 249,611. Patented Nov. 15,1881.

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(No Model.) 2 Sheets-Sheet 2.

W. J. GREEN.

I TELEPHONE SYSTEM. No. 249,611. 1 Patented Nov. 15,1881.

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UNITED STATES PATENT OFFICE.

WILLIAM J. GREEhT, OF WASHINGTON, DISTRICT OF COLUMBIA.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 249,611, dated November15, 1881.

Application filed April .26, 1881.

To all whom it may concern:

Be it known that I, WILLIAM J. GREEN, of

Washington, in the District of Columbia, have invented a new andImproved Telephone System 5 and I do hereby declare the following to bea full, clear, and exact description of the same, reference being had tothe accompanying drawings, forming part of this specification, in whichvI Figure l is a view of the invention in elevation; Fig. 2, a top viewof the same; Fig. 3, a view of the signaling-key; Fig. 4, an enlargedplan view, illustrating the working of the system; Fig. 5, a view of apair of the pegs with their flexible connections.

Similar letters of reference in the several figures denote the sameparts.

The object of this invention is to improve the means for connecting,disconnecting, and otherwise operating a series of telephone-lines at acentral station for tbe purpose of economizing time, labor, and expense,and increasing the convenience with which the operations of acentraloffice can be carried on.

Y The invention consists in the new mechanical combinationshereinafterdescribed and claimed.

In the drawings, A indicates a suitable table, upon which is arranged along insulated metal plate or bar, A, capable of conducting electriccurrents. A series of short conducting bars or plates, 1 3 5 7 9 11,&c., are arranged on either side of the main plate A, but insulated fromeach other andfrom said main plate. A series of similar metalconductingplates, 2 4 6 8 1O 12, are arranged adjacent to the smallplates first mentioned, so as to be readily put into electric connectiontherewith by means of suitable switches or pegs. The annunciator B isput in connection with the plates24 6 8 10 12. The subscribers lines areseverally put in connection with the plates 1 3 5 7 9 11. The mainplate-Ais connected by a suitable conductor, 0, and switch D to themagneto-instrument M and to the telephone T, which are to be used by theoperator at the central station. The instruments M and T, theannunciator, and the subscribers lines are provided withground-connections, as usual, and each of the subscribers lines, as wellas the cen- (N0 model.)

tral operator's line, 0, has a battery of its own. Each or any number ofthe subscribers may use a magneto-machine instead of a batteryforgenerating the current over his line, both arrangements operatingequally well. Conducting-pegs Pare employed to effect the elec tricconnection of the different plates upon the table A, said pegs beingadapted to enter suitable sockets or holes, a b c d of g h ij kl.

In the operation of this apparatus the conducting-pegs are normallyarranged in the holes a b c 61 cf, but not in the other holes, and theswitch Dis arranged to put the telephone T in electric connection withthe main plate A. In such case, when the subscriber ca1ls-for example,the subscriber on line No. 3thecurrent upon line No. 3 comes in throughplate No. 5, through which said line is connected, passes in throughplug in hole cto plate No. 6, and then through the wire extending fromthat plate to the signal No. 3 of the annunciator, causing theannunciator to indicate to the central operator the line from which thecall is made. Thereupon the operator changes the conducting-peg from the'hole 0 to the hole 2', thereby insulating No. 6 and putting plate No. 5into electrical communication with the main plate A, and through saidmain plate with the telephone T. Inquiringthroughthetelephone, he thenlearns from the subscriber that the latter desires to be put intocommunication with another subscriber-for example, on line No.6--whereupon he moves the peg from the hole 1' back to the hole 0, andthen moves the peg from hole f to the hole 1, thereby putting line No. 6in electrical communication with the main plate A and insulating thelatter from all lines save the one called. He then switches in hismagneto-instrument and signals the number of the subscriber who iswanted on line No. 6, after which he puts the peg from hole 0 back tohole 73. The two subscribers are thus put into direct communication witheach other through their respective instruments and lines and throughthe common conductor A. If, now, while the lines of these twosubscribers are in communication with each other, a call from anotherline is indicated by the annunciator, the central operator, firstsatisfying himself that the said two subscribers have finished talkingwith each other, by listening at his own telephone, transfers the pegsfrom holes t" and I back to holes v 'c andf, so as to throw out thelines 3 and 6, and then puts the line on which the new call is made intoconnection with the main plate A, by transfer of the appropriate peg,after which he calls up the subscriber in the desired line, as before.

To enable two or more pairs of subscribers to hold communication witheach other at the same time, it is only necessary to cut out the mainplate and connect the pegs directly with each other. This I accomplishin a very simple manner by constructing one side of the pegs ofconducting material and the other side of non-conducting material andconnecting the two pegs by means of a flexible connection, as shown inFig. 5. By inserting these pegs in the holes with their non-conduetin gsides hearing against the main plate, the said plate will be cut out,and the current, instead of passing through the pins and then throughthe main plate,will pass from one pinto the other through the flexibleconnection. The main plate, being thus cut out, is left entirely free,and any other two subscribers can be put into communication eitherthrough it by the employment of the ordinary pegs, or by another set ofinsulated pegs havingflexible connections, and so on, any number ofpairs of subscribers being allowed to communicate with each other at thesame time. By simply turning the two-part pegs in their holes, so thatthe conducting half of each will be brought into contact with both themain plate and the small plate, the central operator, by

listening at his telephone, isenabled to ascertain whether or not anypair of subscribers have finished communicating, and if they have to cutthem out by transferring their pegs.

By the apparatus herein described the central operator is enabled tocall up all the subscribers lines or as many as he pleases at one andthe same time, and to communicate with them all simultaneously. Toaccomplish this it is only necessary to connect each line-plate to themain plate A. When so connected any communication by him through thetelephone T will be heard by all the subscribers who are connected tothe main plate, and any words spoken through any one of the connectedtelephones will be heard by all the others. Of course, if two shouldundertake to speak at the same time, the sounds would be somewhatconfused, but otherwise the connection is perfeet.

The form of switch by which connection is made between the wireextending from the main plate to the magneto-instrument and to thecentral operators telephoneis immaterial, though I preferably employ forsuch purpose a telegraph-key, K, (shown in Fig. 3,) connecting the wirefrom the main plate to the center of the key, the telephone-wire to theinsulated post 15 at the end with which the normally-depressed end ofthe key engages, and the wire of the magneto-instrument to the insulatedpost a at the other end. When the key is in normal position thetelephone is in communi' cation with the main plate A; but when it isdesired to use the magneto-instrument to send a signal the key isdepressed, whereupon the telephone is cut out and the magneto-instrumentbrought into effective connection with the wire leading to the plate A.

Instead of employing pins or pegs for effecting the connection betweenthe various plates of the apparatus, any suitable form of connection maybe employedsuch, for instance, as ordinary piy oted switch-arms.

In an apparatus now in operation adapted to the control of twenty-fivelines or circuits the various plates, switch, magneto instrument, andtelephone are all arranged upon a table no larger than an ordinarysewing-machine table, and the central operator is enabled to make thenecessary connections and calls with great ease and celerity withoutleav in g his seat.

The capacity of the apparatus can be increased indefinitely byconnecting with the main plate A other main plates, A each having theappropriate number of pairs of small plates arranged alongside it, asshown in Fig. 4.

While the form of the parts and their arrangement as herein shown hasproved very convenient in actual practice, yet I do not limit theinvention thereto, as the form and arrangement of the plates may bemodified indefinitely, and yet produce the same practical results.

The main principle of the invention consists in bringing all the centralterminals of the subscribers lines to a central table or stand, at whichthe operator can sit, and there connecting to a set of exposed insulatedplates provided with means for electrically connecting said plates inpairs and with a common conductor, by which any or all of them can beput into connect-ion with the central operators telephone andsignaling-instrument.

I claim as my invention- 1. In a telephone system, the combination at acentral station of a common conductor, a series of conductors with whicha series of telephone-lines are connected, a second series of conductorsconnected to an annunciator, an annuneiator, and a series of switchesfor connecting and disconnecting the annuneiator-eonductors with theline-conductors and the latter with the common conductor, substantiallyas described.

2. In a telephone system, the combination of the common conductorA withthe line-plates 1 3 5, &c., the annunciator-plates 2 4 6, &c., theannunciator and its connections, the telephone-lines, and the pegs orswitches for conmeeting or disconnecting, substantially as described.

3. The combination of the main conductingplateand small plates alongsidesaid main plate with pegs having one side of conducting material and theother side of non-con- 5 ducting material, and the flexible connectionsbetween the pegs, whereby the main plate may be cut out entirely, or bysimply l turning the pegs broughtin at anytime by the central operator,substantially as described, for the purpose specified.

WM. J. GREEN. Witnesses:

JOSEPH FORREST, WM. A. BLAOKSTOCK.

